In the mid-1800s English doctor John Langdon Down was appointed director of a home outside London for mentally handicapped children, where he studied their symptoms. In 1862 he described the case of one of his wards who was short and had stubby fingers and unusual eyelids. The boy's condition was later labeled with his surname. But the genetic cause of Down syndrome was not uncovered for another century. In 1959 French pediatrician Jrome Lejeune discovered that these children have three copies of chromosome 21, instead of the standard two.

For too long, people with Down syndrome, or trisomy 21, have been dismissed as retarded and thus incapable of having rich lives. But that view has begun to change. Psychologists, doctors and special-education teachers now realize that a diagnosis at infancy does not necessarily mean a child will have few options in life--as long as he receives special training early. And socially, Down syndrome children are finally being accepted as unspectacular, everyday kids, in part thanks to the 1990s hit ABC television series Life Goes On, starring an actor with Down syndrome, Chris Burke, who today is 40.